title: Effects of different progestogens on human breast tumor cell growth.
abstract: OBJECTIVE
  To examine the effect of progestogens currently used in hormone therapy on growth of human breast tumor cells.
  
  
  METHODS
  MCF-7 cells were incubated in 10 nmol/l progestogens, including progesterone (P4), medroxyprogesterone acetate (MPA), norethisterone acetate (NETA), and cyproterone acetate (CPA), with or without 17β-estradiol (E(2), 1 nmol/l and 10 nmol/l), as well as E(2) alone. Cell proliferation, apoptosis, and the expression of caspase-3 and proliferating cell nuclear antigen (PCNA) were evaluated.
  
  
  RESULTS
  The ratios of apoptosis : proliferation significantly increased in cultures with progestogens alone, 1 nmol/l E(2) plus progestogens (except P4), and 10 nmol/l E(2) plus NETA. Caspase-3 significantly diminished in cultures with E(2) alone; this was completely reversed when progestogens were added. MPA alone or with 1 nmol/l E(2) and 10 nmol/l E(2) plus NETA significantly increased caspase-3. Using progestogens alone, except P4, significantly decreased PCNA expression.
  
  
  CONCLUSIONS
  The results demonstrate that various progestogens have different effects on growth of breast tumor cells, especially with the combined usage of E(2). Progestogen-induced apoptosis may be partly inhibited with the presence of E(2), but less severe with lower E(2) concentrations. Therefore, the choice of progestogens, as well as the doses of E(2) and/or progestogen, may influence breast cancer risk.
authors.affiliation: Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital, Keelung and Chang Gung University Taiwan, Republic of China.
authors.forename: F-P
authors.initials: FP
authors.lastname: Chen
authors.forename: M-H
authors.initials: MH
authors.lastname: Chien
authors.forename: H-Y
authors.initials: HY
authors.lastname: Chen
authors.forename: Y-T
authors.initials: YT
authors.lastname: Ng
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D011372:Progestins / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D018931:Antineoplastic Agents, Hormonal; D011372:Progestins; D004958:Estradiol; D053148:Caspase 3